Collection Class
 

Provides the base class for a generic collection.

Namespace:   System.Collections.ObjectModel
Assembly:  mscorlib (in mscorlib.dll)

Inheritance Hierarchy
SystemObject
  System.Collections.ObjectModelCollection
     System.Collections.ObjectModelKeyedCollection
     System.Collections.ObjectModelObservableCollection
     System.ComponentModelBindingList
     System.ComponentModelSortDescriptionCollection
     System.IdentityModel.Protocols.WSTrustRequestClaimCollection
     System.IdentityModel.TokensSecurityTokenHandlerCollection
     System.NetIPEndPointCollection
     System.Net.MailAlternateViewCollection
     System.Net.MailAttachmentCollection
     System.Net.MailLinkedResourceCollection
     System.Net.MailMailAddressCollection
     System.Net.PeerToPeerCloudCollection
     System.Net.PeerToPeer.CollaborationPeerApplicationCollection
     System.Net.PeerToPeer.CollaborationPeerContactCollection
     System.Net.PeerToPeer.CollaborationPeerEndPointCollection
     System.Net.PeerToPeer.CollaborationPeerNearMeCollection
     System.Net.PeerToPeer.CollaborationPeerObjectCollection
     System.Net.PeerToPeerPeerNameRecordCollection
     System.Security.CryptographyCngPropertyCollection
     System.ServiceModel.ChannelsBindingElementCollection
     System.ServiceModel.ChannelsChannelParameterCollection
     System.ServiceModel.DescriptionFaultDescriptionCollection
     System.ServiceModel.DescriptionMessageDescriptionCollection
     System.ServiceModel.DescriptionOperationDescriptionCollection
     System.ServiceModel.DescriptionPolicyAssertionCollection
     System.ServiceModel.DescriptionServiceEndpointCollection
     System.ServiceModel.DispatcherMessageQueryCollection
     System.ServiceModel.SyndicationSyndicationElementExtensionCollection
     System.Web.DynamicDataDataControlReferenceCollection
     System.Web.ModelBindingModelBinderProviderCollection
     System.Web.ModelBindingModelErrorCollection
     System.Web.ModelBindingModelValidatorProviderCollection
     System.Web.ModelBindingValueProviderCollection
     System.Web.RoutingRouteCollection
     System.Web.UI.DataVisualization.ChartingChartElementCollection
     System.Web.UIScriptReferenceCollection
     System.Web.UIServiceReferenceCollection
     System.Web.UIUpdatePanelTriggerCollection
     System.WindowsConditionCollection
     System.Windows.Forms.DataVisualization.ChartingChartElementCollection
     System.Windows.FormsFileDialogCustomPlacesCollection
     System.Windows.InkStrokeCollection
     System.Windows.Input.StylusPlugInsStylusPlugInCollection
     System.Windows.InputStylusPointCollection
     System.Windows.InputTouchPointCollection
     System.WindowsSetterBaseCollection
     System.WindowsTriggerCollection
     System.Workflow.ComponentModel.CompilerValidationErrorCollection

Syntax
[SerializableAttribute]
[ComVisibleAttribute(false)]
public class Collection<T> : IList<T>, ICollection<T>, IEnumerable<T>, 
	IEnumerable, IList, ICollection, IReadOnlyList<T>, IReadOnlyCollection<T>
generic<typename T>
[SerializableAttribute]
[ComVisibleAttribute(false)]
public ref class Collection : IList<T>, ICollection<T>, IEnumerable<T>, 
	IEnumerable, IList, ICollection, IReadOnlyList<T>, IReadOnlyCollection<T>
[<SerializableAttribute>]
[<ComVisibleAttribute(false)>]
type Collection<'T> = 
    class
        interface IList<'T>
        interface ICollection<'T>
        interface IEnumerable<'T>
        interface IEnumerable
        interface IList
        interface ICollection
        interface IReadOnlyList<'T>
        interface IReadOnlyCollection<'T>
    end
<SerializableAttribute>
<ComVisibleAttribute(False)>
Public Class Collection(Of T)
	Implements IList(Of T), ICollection(Of T), IEnumerable(Of T), IEnumerable,
	IList, ICollection, IReadOnlyList(Of T), IReadOnlyCollection(Of T)

Type Parameters

T

The type of elements in the collection.

Constructors
NameDescription
System_CAPS_pubmethod Collection

Initializes a new instance of the Collection class that is empty.

System_CAPS_pubmethod Collection

Initializes a new instance of the Collection class as a wrapper for the specified list.

Properties
NameDescription
System_CAPS_pubproperty

Gets the number of elements actually contained in the Collection.

System_CAPS_pubproperty

Gets or sets the element at the specified index.

System_CAPS_protproperty

Gets a IList wrapper around the Collection.

Methods
NameDescription
System_CAPS_pubmethod Add

Adds an object to the end of the Collection.

System_CAPS_pubmethod Clear

Removes all elements from the Collection.

System_CAPS_protmethod ClearItems

Removes all elements from the Collection.

System_CAPS_pubmethod Contains

Determines whether an element is in the Collection.

System_CAPS_pubmethod CopyTo

Copies the entire Collection to a compatible one-dimensional Array, starting at the specified index of the target array.

System_CAPS_pubmethod Equals

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_protmethod Finalize

Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)

System_CAPS_pubmethod GetEnumerator

Returns an enumerator that iterates through the Collection.

System_CAPS_pubmethod GetHashCode

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethod GetType

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethod IndexOf

Searches for the specified object and returns the zero-based index of the first occurrence within the entire Collection.

System_CAPS_pubmethod Insert

Inserts an element into the Collection at the specified index.

System_CAPS_protmethod InsertItem

Inserts an element into the Collection at the specified index.

System_CAPS_protmethod MemberwiseClone

Creates a shallow copy of the current Object.(Inherited from Object.)

System_CAPS_pubmethod Remove

Removes the first occurrence of a specific object from the Collection.

System_CAPS_pubmethod RemoveAt

Removes the element at the specified index of the Collection.

System_CAPS_protmethod RemoveItem

Removes the element at the specified index of the Collection.

System_CAPS_protmethod SetItem

Replaces the element at the specified index.

System_CAPS_pubmethod ToString

Returns a string that represents the current object.(Inherited from Object.)

Explicit Interface Implementations
NameDescription
System_CAPS_pubinterface System_CAPS_privmethod ICollectionCopyTo

Copies the elements of the ICollection to an Array, starting at a particular Array index.

System_CAPS_pubinterface System_CAPS_privmethod IEnumerableGetEnumerator

Returns an enumerator that iterates through a collection.

System_CAPS_pubinterface System_CAPS_privmethod IListAdd

Adds an item to the IList.

System_CAPS_pubinterface System_CAPS_privmethod IListContains

Determines whether the IList contains a specific value.

System_CAPS_pubinterface System_CAPS_privmethod IListIndexOf

Determines the index of a specific item in the IList.

System_CAPS_pubinterface System_CAPS_privmethod IListInsert

Inserts an item into the IList at the specified index.

System_CAPS_pubinterface System_CAPS_privmethod IListRemove

Removes the first occurrence of a specific object from the IList.

System_CAPS_pubinterface System_CAPS_privproperty

Gets a value indicating whether the ICollection is read-only.

System_CAPS_pubinterface System_CAPS_privproperty

Gets a value indicating whether access to the ICollection is synchronized (thread safe).

System_CAPS_pubinterface System_CAPS_privproperty

Gets an object that can be used to synchronize access to the ICollection.

System_CAPS_pubinterface System_CAPS_privproperty

Gets a value indicating whether the IList has a fixed size.

System_CAPS_pubinterface System_CAPS_privproperty

Gets a value indicating whether the IList is read-only.

System_CAPS_pubinterface System_CAPS_privproperty

Gets or sets the element at the specified index.

Extension Methods
NameDescription
System_CAPS_pubmethod Aggregate

Overloaded. Applies an accumulator function over a sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Aggregate

Overloaded. Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value.(Defined by Enumerable.)

System_CAPS_pubmethod Aggregate

Overloaded. Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value.(Defined by Enumerable.)

System_CAPS_pubmethod All

Determines whether all elements of a sequence satisfy a condition.(Defined by Enumerable.)

System_CAPS_pubmethod Any

Overloaded. Determines whether a sequence contains any elements.(Defined by Enumerable.)

System_CAPS_pubmethod Any

Overloaded. Determines whether any element of a sequence satisfies a condition.(Defined by Enumerable.)

System_CAPS_pubmethod AsEnumerable

Returns the input typed as IEnumerable.(Defined by Enumerable.)

System_CAPS_pubmethod AsParallel

Overloaded. Enables parallelization of a query.(Defined by ParallelEnumerable.)

System_CAPS_pubmethod AsParallel

Overloaded. Enables parallelization of a query.(Defined by ParallelEnumerable.)

System_CAPS_pubmethod AsQueryable

Overloaded. Converts an IEnumerable to an IQueryable.(Defined by Queryable.)

System_CAPS_pubmethod AsQueryable

Overloaded. Converts a generic IEnumerable to a generic IQueryable.(Defined by Queryable.)

System_CAPS_pubmethod Average

Overloaded. Computes the average of a sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Average

Overloaded. Computes the average of a sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Average

Overloaded. Computes the average of a sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Average

Overloaded. Computes the average of a sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Average

Overloaded. Computes the average of a sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Average

Overloaded. Computes the average of a sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Average

Overloaded. Computes the average of a sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Average

Overloaded. Computes the average of a sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Average

Overloaded. Computes the average of a sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Average

Overloaded. Computes the average of a sequence of Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Cast

Casts the elements of an IEnumerable to the specified type.(Defined by Enumerable.)

System_CAPS_pubmethod Concat

Concatenates two sequences.(Defined by Enumerable.)

System_CAPS_pubmethod Contains

Overloaded. Determines whether a sequence contains a specified element by using the default equality comparer.(Defined by Enumerable.)

System_CAPS_pubmethod Contains

Overloaded. Determines whether a sequence contains a specified element by using a specified IEqualityComparer.(Defined by Enumerable.)

System_CAPS_pubmethod Count

Overloaded. Returns the number of elements in a sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Count

Overloaded. Returns a number that represents how many elements in the specified sequence satisfy a condition.(Defined by Enumerable.)

System_CAPS_pubmethod DefaultIfEmpty

Overloaded. Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty.(Defined by Enumerable.)

System_CAPS_pubmethod DefaultIfEmpty

Overloaded. Returns the elements of the specified sequence or the specified value in a singleton collection if the sequence is empty.(Defined by Enumerable.)

System_CAPS_pubmethod Distinct

Overloaded. Returns distinct elements from a sequence by using the default equality comparer to compare values.(Defined by Enumerable.)

System_CAPS_pubmethod Distinct

Overloaded. Returns distinct elements from a sequence by using a specified IEqualityComparer to compare values.(Defined by Enumerable.)

System_CAPS_pubmethod ElementAt

Returns the element at a specified index in a sequence.(Defined by Enumerable.)

System_CAPS_pubmethod ElementAtOrDefault

Returns the element at a specified index in a sequence or a default value if the index is out of range.(Defined by Enumerable.)

System_CAPS_pubmethod Except

Overloaded. Produces the set difference of two sequences by using the default equality comparer to compare values.(Defined by Enumerable.)

System_CAPS_pubmethod Except

Overloaded. Produces the set difference of two sequences by using the specified IEqualityComparer to compare values.(Defined by Enumerable.)

System_CAPS_pubmethod First

Overloaded. Returns the first element of a sequence.(Defined by Enumerable.)

System_CAPS_pubmethod First

Overloaded. Returns the first element in a sequence that satisfies a specified condition.(Defined by Enumerable.)

System_CAPS_pubmethod FirstOrDefault

Overloaded. Returns the first element of a sequence, or a default value if the sequence contains no elements.(Defined by Enumerable.)

System_CAPS_pubmethod FirstOrDefault

Overloaded. Returns the first element of the sequence that satisfies a condition or a default value if no such element is found.(Defined by Enumerable.)

System_CAPS_pubmethod GroupBy

Overloaded. Groups the elements of a sequence according to a specified key selector function.(Defined by Enumerable.)

System_CAPS_pubmethod GroupBy

Overloaded. Groups the elements of a sequence according to a specified key selector function and compares the keys by using a specified comparer.(Defined by Enumerable.)

System_CAPS_pubmethod GroupBy

Overloaded. Groups the elements of a sequence according to a specified key selector function and projects the elements for each group by using a specified function.(Defined by Enumerable.)

System_CAPS_pubmethod GroupBy

Overloaded. Groups the elements of a sequence according to a key selector function. The keys are compared by using a comparer and each group's elements are projected by using a specified function.(Defined by Enumerable.)

System_CAPS_pubmethod GroupBy

Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key.(Defined by Enumerable.)

System_CAPS_pubmethod GroupBy

Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The keys are compared by using a specified comparer.(Defined by Enumerable.)

System_CAPS_pubmethod GroupBy

Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The elements of each group are projected by using a specified function.(Defined by Enumerable.)

System_CAPS_pubmethod GroupBy

Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. Key values are compared by using a specified comparer, and the elements of each group are projected by using a specified function.(Defined by Enumerable.)

System_CAPS_pubmethod GroupJoin

Overloaded. Correlates the elements of two sequences based on equality of keys and groups the results. The default equality comparer is used to compare keys.(Defined by Enumerable.)

System_CAPS_pubmethod GroupJoin

Overloaded. Correlates the elements of two sequences based on key equality and groups the results. A specified IEqualityComparer is used to compare keys.(Defined by Enumerable.)

System_CAPS_pubmethod Intersect

Overloaded. Produces the set intersection of two sequences by using the default equality comparer to compare values.(Defined by Enumerable.)

System_CAPS_pubmethod Intersect

Overloaded. Produces the set intersection of two sequences by using the specified IEqualityComparer to compare values.(Defined by Enumerable.)

System_CAPS_pubmethod Join

Overloaded. Correlates the elements of two sequences based on matching keys. The default equality comparer is used to compare keys.(Defined by Enumerable.)

System_CAPS_pubmethod Join

Overloaded. Correlates the elements of two sequences based on matching keys. A specified IEqualityComparer is used to compare keys.(Defined by Enumerable.)

System_CAPS_pubmethod Last

Overloaded. Returns the last element of a sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Last

Overloaded. Returns the last element of a sequence that satisfies a specified condition.(Defined by Enumerable.)

System_CAPS_pubmethod LastOrDefault

Overloaded. Returns the last element of a sequence, or a default value if the sequence contains no elements.(Defined by Enumerable.)

System_CAPS_pubmethod LastOrDefault

Overloaded. Returns the last element of a sequence that satisfies a condition or a default value if no such element is found.(Defined by Enumerable.)

System_CAPS_pubmethod LongCount

Overloaded. Returns an Int64 that represents the total number of elements in a sequence.(Defined by Enumerable.)

System_CAPS_pubmethod LongCount

Overloaded. Returns an Int64 that represents how many elements in a sequence satisfy a condition.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Returns the maximum value in a generic sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Decimal value.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Double value.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Int32 value.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Int64 value.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Decimal value.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Double value.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Int32 value.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Int64 value.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Single value.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Single value.(Defined by Enumerable.)

System_CAPS_pubmethod Max

Overloaded. Invokes a transform function on each element of a generic sequence and returns the maximum resulting value.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Returns the minimum value in a generic sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Decimal value.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Double value.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Int32 value.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Int64 value.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Decimal value.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Double value.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Int32 value.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Int64 value.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Single value.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Single value.(Defined by Enumerable.)

System_CAPS_pubmethod Min

Overloaded. Invokes a transform function on each element of a generic sequence and returns the minimum resulting value.(Defined by Enumerable.)

System_CAPS_pubmethod OfType

Filters the elements of an IEnumerable based on a specified type.(Defined by Enumerable.)

System_CAPS_pubmethod OrderBy

Overloaded. Sorts the elements of a sequence in ascending order according to a key.(Defined by Enumerable.)

System_CAPS_pubmethod OrderBy

Overloaded. Sorts the elements of a sequence in ascending order by using a specified comparer.(Defined by Enumerable.)

System_CAPS_pubmethod OrderByDescending

Overloaded. Sorts the elements of a sequence in descending order according to a key.(Defined by Enumerable.)

System_CAPS_pubmethod OrderByDescending

Overloaded. Sorts the elements of a sequence in descending order by using a specified comparer.(Defined by Enumerable.)

System_CAPS_pubmethod Reverse

Inverts the order of the elements in a sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Select

Overloaded. Projects each element of a sequence into a new form.(Defined by Enumerable.)

System_CAPS_pubmethod Select

Overloaded. Projects each element of a sequence into a new form by incorporating the element's index.(Defined by Enumerable.)

System_CAPS_pubmethod SelectMany

Overloaded. Projects each element of a sequence to an IEnumerable and flattens the resulting sequences into one sequence.(Defined by Enumerable.)

System_CAPS_pubmethod SelectMany

Overloaded. Projects each element of a sequence to an IEnumerable, and flattens the resulting sequences into one sequence. The index of each source element is used in the projected form of that element.(Defined by Enumerable.)

System_CAPS_pubmethod SelectMany

Overloaded. Projects each element of a sequence to an IEnumerable, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein.(Defined by Enumerable.)

System_CAPS_pubmethod SelectMany

Overloaded. Projects each element of a sequence to an IEnumerable, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. The index of each source element is used in the intermediate projected form of that element.(Defined by Enumerable.)

System_CAPS_pubmethod SequenceEqual

Overloaded. Determines whether two sequences are equal by comparing the elements by using the default equality comparer for their type.(Defined by Enumerable.)

System_CAPS_pubmethod SequenceEqual

Overloaded. Determines whether two sequences are equal by comparing their elements by using a specified IEqualityComparer.(Defined by Enumerable.)

System_CAPS_pubmethod Single

Overloaded. Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Single

Overloaded. Returns the only element of a sequence that satisfies a specified condition, and throws an exception if more than one such element exists.(Defined by Enumerable.)

System_CAPS_pubmethod SingleOrDefault

Overloaded. Returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.(Defined by Enumerable.)

System_CAPS_pubmethod SingleOrDefault

Overloaded. Returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.(Defined by Enumerable.)

System_CAPS_pubmethod Skip

Bypasses a specified number of elements in a sequence and then returns the remaining elements.(Defined by Enumerable.)

System_CAPS_pubmethod SkipWhile

Overloaded. Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements.(Defined by Enumerable.)

System_CAPS_pubmethod SkipWhile

Overloaded. Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. The element's index is used in the logic of the predicate function.(Defined by Enumerable.)

System_CAPS_pubmethod Sum

Overloaded. Computes the sum of the sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Sum

Overloaded. Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Sum

Overloaded. Computes the sum of the sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Sum

Overloaded. Computes the sum of the sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Sum

Overloaded. Computes the sum of the sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Sum

Overloaded. Computes the sum of the sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Sum

Overloaded. Computes the sum of the sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Sum

Overloaded. Computes the sum of the sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Sum

Overloaded. Computes the sum of the sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Sum

Overloaded. Computes the sum of the sequence of Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)

System_CAPS_pubmethod Take

Returns a specified number of contiguous elements from the start of a sequence.(Defined by Enumerable.)

System_CAPS_pubmethod TakeWhile

Overloaded. Returns elements from a sequence as long as a specified condition is true.(Defined by Enumerable.)

System_CAPS_pubmethod TakeWhile

Overloaded. Returns elements from a sequence as long as a specified condition is true. The element's index is used in the logic of the predicate function.(Defined by Enumerable.)

System_CAPS_pubmethod ToArray

Creates an array from a IEnumerable.(Defined by Enumerable.)

System_CAPS_pubmethod ToDictionary

Overloaded. Creates a Dictionary from an IEnumerable according to a specified key selector function.(Defined by Enumerable.)

System_CAPS_pubmethod ToDictionary

Overloaded. Creates a Dictionary from an IEnumerable according to a specified key selector function and key comparer.(Defined by Enumerable.)

System_CAPS_pubmethod ToDictionary

Overloaded. Creates a Dictionary from an IEnumerable according to specified key selector and element selector functions.(Defined by Enumerable.)

System_CAPS_pubmethod ToDictionary

Overloaded. Creates a Dictionary from an IEnumerable according to a specified key selector function, a comparer, and an element selector function.(Defined by Enumerable.)

System_CAPS_pubmethod ToList

Creates a List from an IEnumerable.(Defined by Enumerable.)

System_CAPS_pubmethod ToLookup

Overloaded. Creates a Lookup from an IEnumerable according to a specified key selector function.(Defined by Enumerable.)

System_CAPS_pubmethod ToLookup

Overloaded. Creates a Lookup from an IEnumerable according to a specified key selector function and key comparer.(Defined by Enumerable.)

System_CAPS_pubmethod ToLookup

Overloaded. Creates a Lookup from an IEnumerable according to specified key selector and element selector functions.(Defined by Enumerable.)

System_CAPS_pubmethod ToLookup

Overloaded. Creates a Lookup from an IEnumerable according to a specified key selector function, a comparer and an element selector function.(Defined by Enumerable.)

System_CAPS_pubmethod Union

Overloaded. Produces the set union of two sequences by using the default equality comparer.(Defined by Enumerable.)

System_CAPS_pubmethod Union

Overloaded. Produces the set union of two sequences by using a specified IEqualityComparer.(Defined by Enumerable.)

System_CAPS_pubmethod Where

Overloaded. Filters a sequence of values based on a predicate.(Defined by Enumerable.)

System_CAPS_pubmethod Where

Overloaded. Filters a sequence of values based on a predicate. Each element's index is used in the logic of the predicate function.(Defined by Enumerable.)

System_CAPS_pubmethod Zip

Applies a specified function to the corresponding elements of two sequences, producing a sequence of the results.(Defined by Enumerable.)

Remarks

The Collection class can be used immediately by creating an instance of one of its constructed types; all you have to do is specify the type of object to be contained in the collection. In addition, you can derive your own collection type from any constructed type, or derive a generic collection type from the Collection class itself.

The Collection class provides protected methods that can be used to customize its behavior when adding and removing items, clearing the collection, or setting the value of an existing item.

Most Collection objectscan be modified. However, a Collection object that is initialized with a read-only IList object cannot be modified. See ReadOnlyCollection for a read-only version of this class.

Elements in this collection can be accessed using an integer index. Indexes in this collection are zero-based.

Collection accepts null as a valid value for reference types and allows duplicate elements.

Notes to Implementers:

This base class is provided to make it easier for implementers to create a custom collection. Implementers are encouraged to extend this base class instead of creating their own.

Examples

This section contains two code examples. The first example demonstrates several properties and methods of the Collection class. The second example shows how to derive a collection class from a constructed type of Collection, and how to override the protected methods of Collection to provide custom behavior.

Example 1

The following code example demonstrates many of the properties and methods of Collection. The code example creates a collection of strings, uses the Add method to add several strings, displays the , and lists the strings. The example uses the IndexOf method to find the index of a string and the Contains method to determine whether a string is in the collection. The example inserts a string using the Insert method and retrieves and sets strings using the default property (the indexer in C#). The example removes strings by string identity using the Remove method and by index using the RemoveAt method. Finally, the Clear method is used to clear all strings from the collection.

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;

public class Demo
{
    public static void Main()
    {
        Collection<string> dinosaurs = new Collection<string>();

        dinosaurs.Add("Psitticosaurus");
        dinosaurs.Add("Caudipteryx");
        dinosaurs.Add("Compsognathus");
        dinosaurs.Add("Muttaburrasaurus");

        Console.WriteLine("{0} dinosaurs:", dinosaurs.Count);
        Display(dinosaurs);

        Console.WriteLine("\nIndexOf(\"Muttaburrasaurus\"): {0}", 
            dinosaurs.IndexOf("Muttaburrasaurus"));

        Console.WriteLine("\nContains(\"Caudipteryx\"): {0}", 
            dinosaurs.Contains("Caudipteryx"));

        Console.WriteLine("\nInsert(2, \"Nanotyrannus\")");
        dinosaurs.Insert(2, "Nanotyrannus");
        Display(dinosaurs);

        Console.WriteLine("\ndinosaurs[2]: {0}", dinosaurs[2]);

        Console.WriteLine("\ndinosaurs[2] = \"Microraptor\"");
        dinosaurs[2] = "Microraptor";
        Display(dinosaurs);

        Console.WriteLine("\nRemove(\"Microraptor\")");
        dinosaurs.Remove("Microraptor");
        Display(dinosaurs);

        Console.WriteLine("\nRemoveAt(0)");
        dinosaurs.RemoveAt(0);
        Display(dinosaurs);

        Console.WriteLine("\ndinosaurs.Clear()");
        dinosaurs.Clear();
        Console.WriteLine("Count: {0}", dinosaurs.Count);
    }

    private static void Display(Collection<string> cs)
    {
        Console.WriteLine();
        foreach( string item in cs )
        {
            Console.WriteLine(item);
        }
    }
}

/* This code example produces the following output:

4 dinosaurs:

Psitticosaurus
Caudipteryx
Compsognathus
Muttaburrasaurus

IndexOf("Muttaburrasaurus"): 3

Contains("Caudipteryx"): True

Insert(2, "Nanotyrannus")

Psitticosaurus
Caudipteryx
Nanotyrannus
Compsognathus
Muttaburrasaurus

dinosaurs[2]: Nanotyrannus

dinosaurs[2] = "Microraptor"

Psitticosaurus
Caudipteryx
Microraptor
Compsognathus
Muttaburrasaurus

Remove("Microraptor")

Psitticosaurus
Caudipteryx
Compsognathus
Muttaburrasaurus

RemoveAt(0)

Caudipteryx
Compsognathus
Muttaburrasaurus

dinosaurs.Clear()
Count: 0
 */
Imports System
Imports System.Collections.Generic
Imports System.Collections.ObjectModel

Public Class Demo

    Public Shared Sub Main() 

        Dim dinosaurs As New Collection(Of String)

        dinosaurs.Add("Psitticosaurus")
        dinosaurs.Add("Caudipteryx")
        dinosaurs.Add("Compsognathus")
        dinosaurs.Add("Muttaburrasaurus")

        Console.WriteLine("{0} dinosaurs:", dinosaurs.Count)
        Display(dinosaurs)

        Console.WriteLine(vbLf & "IndexOf(""Muttaburrasaurus""): {0}", _
            dinosaurs.IndexOf("Muttaburrasaurus"))

        Console.WriteLine(vbLf & "Contains(""Caudipteryx""): {0}", _
            dinosaurs.Contains("Caudipteryx"))

        Console.WriteLine(vbLf & "Insert(2, ""Nanotyrannus"")")
        dinosaurs.Insert(2, "Nanotyrannus")
        Display(dinosaurs)

        Console.WriteLine(vbLf & "dinosaurs(2): {0}", dinosaurs(2))

        Console.WriteLine(vbLf & "dinosaurs(2) = ""Microraptor""")
        dinosaurs(2) = "Microraptor"
        Display(dinosaurs)

        Console.WriteLine(vbLf & "Remove(""Microraptor"")")
        dinosaurs.Remove("Microraptor")
        Display(dinosaurs)

        Console.WriteLine(vbLf & "RemoveAt(0)")
        dinosaurs.RemoveAt(0)
        Display(dinosaurs)

        Console.WriteLine(vbLf & "dinosaurs.Clear()")
        dinosaurs.Clear()
        Console.WriteLine("Count: {0}", dinosaurs.Count)

    End Sub

    Private Shared Sub Display(ByVal cs As Collection(Of String)) 
        Console.WriteLine()
        For Each item As String In cs
            Console.WriteLine(item)
        Next item
    End Sub
End Class

' This code example produces the following output:
'
'4 dinosaurs:
'
'Psitticosaurus
'Caudipteryx
'Compsognathus
'Muttaburrasaurus
'
'IndexOf("Muttaburrasaurus"): 3
'
'Contains("Caudipteryx"): True
'
'Insert(2, "Nanotyrannus")
'
'Psitticosaurus
'Caudipteryx
'Nanotyrannus
'Compsognathus
'Muttaburrasaurus
'
'dinosaurs(2): Nanotyrannus
'
'dinosaurs(2) = "Microraptor"
'
'Psitticosaurus
'Caudipteryx
'Microraptor
'Compsognathus
'Muttaburrasaurus
'
'Remove("Microraptor")
'
'Psitticosaurus
'Caudipteryx
'Compsognathus
'Muttaburrasaurus
'
'RemoveAt(0)
'
'Caudipteryx
'Compsognathus
'Muttaburrasaurus
'
'dinosaurs.Clear()
'Count: 0
using namespace System;
using namespace System::Collections::Generic;
using namespace System::Collections::ObjectModel;

public ref class Demo
{
public:
    static void Main()
    {
        Collection<String^>^ dinosaurs = gcnew Collection<String^>();

        dinosaurs->Add("Psitticosaurus");
        dinosaurs->Add("Caudipteryx");
        dinosaurs->Add("Compsognathus");
        dinosaurs->Add("Muttaburrasaurus");

        Console::WriteLine("{0} dinosaurs:", dinosaurs->Count);
        Display(dinosaurs);

        Console::WriteLine("\nIndexOf(\"Muttaburrasaurus\"): {0}",
            dinosaurs->IndexOf("Muttaburrasaurus"));

        Console::WriteLine("\nContains(\"Caudipteryx\"): {0}",
            dinosaurs->Contains("Caudipteryx"));

        Console::WriteLine("\nInsert(2, \"Nanotyrannus\")");
        dinosaurs->Insert(2, "Nanotyrannus");
        Display(dinosaurs);

        Console::WriteLine("\ndinosaurs[2]: {0}", dinosaurs[2]);

        Console::WriteLine("\ndinosaurs[2] = \"Microraptor\"");
        dinosaurs[2] = "Microraptor";
        Display(dinosaurs);

        Console::WriteLine("\nRemove(\"Microraptor\")");
        dinosaurs->Remove("Microraptor");
        Display(dinosaurs);

        Console::WriteLine("\nRemoveAt(0)");
        dinosaurs->RemoveAt(0);
        Display(dinosaurs);

        Console::WriteLine("\ndinosaurs.Clear()");
        dinosaurs->Clear();
        Console::WriteLine("Count: {0}", dinosaurs->Count);
    }

private:
    static void Display(Collection<String^>^ cs)
    {
        Console::WriteLine();
        for each( String^ item in cs )
        {
            Console::WriteLine(item);
        }
    }
};

int main()
{
    Demo::Main();
}

/* This code example produces the following output:

4 dinosaurs:

Psitticosaurus
Caudipteryx
Compsognathus
Muttaburrasaurus

IndexOf("Muttaburrasaurus"): 3

Contains("Caudipteryx"): True

Insert(2, "Nanotyrannus")

Psitticosaurus
Caudipteryx
Nanotyrannus
Compsognathus
Muttaburrasaurus

dinosaurs[2]: Nanotyrannus

dinosaurs[2] = "Microraptor"

Psitticosaurus
Caudipteryx
Microraptor
Compsognathus
Muttaburrasaurus

Remove("Microraptor")

Psitticosaurus
Caudipteryx
Compsognathus
Muttaburrasaurus

RemoveAt(0)

Caudipteryx
Compsognathus
Muttaburrasaurus

dinosaurs.Clear()
Count: 0
 */

Example 2

The following code example shows how to derive a collection class from a constructed type of the Collection generic class, and how to override the protected InsertItem, RemoveItem, ClearItems, and SetItem methods to provide custom behavior for the Add, Insert, Remove, and Clear methods, and for setting the property.

The custom behavior provided by this example is a Changed notification event that is raised at the end of each of the protected methods. The Dinosaurs class inherits Collection<string> (Collection(Of String) in Visual Basic) and defines the Changed event, which uses a DinosaursChangedEventArgs class for the event information, and an enumeration to identify the kind of change.

The code example calls several properties and methods of Collection to demonstrate the custom event.

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;

public class Dinosaurs : Collection<string>
{
    public event EventHandler<DinosaursChangedEventArgs> Changed;

    protected override void InsertItem(int index, string newItem)
    {
        base.InsertItem(index, newItem);

        EventHandler<DinosaursChangedEventArgs> temp = Changed;
        if (temp != null)
        {
            temp(this, new DinosaursChangedEventArgs(
                ChangeType.Added, newItem, null));
        }
    }

    protected override void SetItem(int index, string newItem)
    {
        string replaced = Items[index];
        base.SetItem(index, newItem);

        EventHandler<DinosaursChangedEventArgs> temp = Changed;
        if (temp != null)
        {
            temp(this, new DinosaursChangedEventArgs(
                ChangeType.Replaced, replaced, newItem));
        }
    }

    protected override void RemoveItem(int index)
    {
        string removedItem = Items[index];
        base.RemoveItem(index);

        EventHandler<DinosaursChangedEventArgs> temp = Changed;
        if (temp != null)
        {
            temp(this, new DinosaursChangedEventArgs(
                ChangeType.Removed, removedItem, null));
        }
    }

    protected override void ClearItems()
    {
        base.ClearItems();

        EventHandler<DinosaursChangedEventArgs> temp = Changed;
        if (temp != null)
        {
            temp(this, new DinosaursChangedEventArgs(
                ChangeType.Cleared, null, null));
        }
    }
}

// Event argument for the Changed event.
//
public class DinosaursChangedEventArgs : EventArgs
{
    public readonly string ChangedItem;
    public readonly ChangeType ChangeType;
    public readonly string ReplacedWith;

    public DinosaursChangedEventArgs(ChangeType change, string item, 
        string replacement)
    {
        ChangeType = change;
        ChangedItem = item;
        ReplacedWith = replacement;
    }
}

public enum ChangeType
{
    Added, 
    Removed, 
    Replaced, 
    Cleared
};

public class Demo
{
    public static void Main()
    {
        Dinosaurs dinosaurs = new Dinosaurs();

        dinosaurs.Changed += ChangedHandler; 

        dinosaurs.Add("Psitticosaurus");
        dinosaurs.Add("Caudipteryx");
        dinosaurs.Add("Compsognathus");
        dinosaurs.Add("Muttaburrasaurus");

        Display(dinosaurs);

        Console.WriteLine("\nIndexOf(\"Muttaburrasaurus\"): {0}", 
            dinosaurs.IndexOf("Muttaburrasaurus"));

        Console.WriteLine("\nContains(\"Caudipteryx\"): {0}", 
            dinosaurs.Contains("Caudipteryx"));

        Console.WriteLine("\nInsert(2, \"Nanotyrannus\")");
        dinosaurs.Insert(2, "Nanotyrannus");

        Console.WriteLine("\ndinosaurs[2]: {0}", dinosaurs[2]);

        Console.WriteLine("\ndinosaurs[2] = \"Microraptor\"");
        dinosaurs[2] = "Microraptor";

        Console.WriteLine("\nRemove(\"Microraptor\")");
        dinosaurs.Remove("Microraptor");

        Console.WriteLine("\nRemoveAt(0)");
        dinosaurs.RemoveAt(0);

        Display(dinosaurs);
    }

    private static void Display(Collection<string> cs)
    {
        Console.WriteLine();
        foreach( string item in cs )
        {
            Console.WriteLine(item);
        }
    }

    private static void ChangedHandler(object source, 
        DinosaursChangedEventArgs e)
    {

        if (e.ChangeType==ChangeType.Replaced)
        {
            Console.WriteLine("{0} was replaced with {1}", e.ChangedItem, 
                e.ReplacedWith);
        }
        else if(e.ChangeType==ChangeType.Cleared)
        {
            Console.WriteLine("The dinosaur list was cleared.");
        }
        else
        {
            Console.WriteLine("{0} was {1}.", e.ChangedItem, e.ChangeType);
        }
    }
}

/* This code example produces the following output:

Psitticosaurus was Added.
Caudipteryx was Added.
Compsognathus was Added.
Muttaburrasaurus was Added.

Psitticosaurus
Caudipteryx
Compsognathus
Muttaburrasaurus

IndexOf("Muttaburrasaurus"): 3

Contains("Caudipteryx"): True

Insert(2, "Nanotyrannus")
Nanotyrannus was Added.

dinosaurs[2]: Nanotyrannus

dinosaurs[2] = "Microraptor"
Nanotyrannus was replaced with Microraptor

Remove("Microraptor")
Microraptor was Removed.

RemoveAt(0)
Psitticosaurus was Removed.

Caudipteryx
Compsognathus
Muttaburrasaurus
 */
Imports System
Imports System.Collections.Generic
Imports System.Collections.ObjectModel

Public Class Dinosaurs
    Inherits Collection(Of String)

    Public Event Changed As EventHandler(Of DinosaursChangedEventArgs)

    Protected Overrides Sub InsertItem( _
        ByVal index As Integer, ByVal newItem As String)

        MyBase.InsertItem(index, newItem)

        RaiseEvent Changed(Me, New DinosaursChangedEventArgs( _
            ChangeType.Added, newItem, Nothing))
    End Sub

    Protected Overrides Sub SetItem(ByVal index As Integer, _
        ByVal newItem As String)

        Dim replaced As String = Items(index)
        MyBase.SetItem(index, newItem)

        RaiseEvent Changed(Me, New DinosaursChangedEventArgs( _
            ChangeType.Replaced, replaced, newItem))
    End Sub

    Protected Overrides Sub RemoveItem(ByVal index As Integer)

        Dim removedItem As String = Items(index)
        MyBase.RemoveItem(index)

        RaiseEvent Changed(Me, New DinosaursChangedEventArgs( _
            ChangeType.Removed, removedItem, Nothing))
    End Sub

    Protected Overrides Sub ClearItems()
        MyBase.ClearItems()

        RaiseEvent Changed(Me, New DinosaursChangedEventArgs( _
            ChangeType.Cleared, Nothing, Nothing))
    End Sub

End Class

' Event argument for the Changed event.
'
Public Class DinosaursChangedEventArgs
    Inherits EventArgs

    Public ReadOnly ChangedItem As String
    Public ReadOnly ChangeType As ChangeType
    Public ReadOnly ReplacedWith As String

    Public Sub New(ByVal change As ChangeType, ByVal item As String, _
        ByVal replacement As String)

        ChangeType = change
        ChangedItem = item
        ReplacedWith = replacement
    End Sub
End Class

Public Enum ChangeType
    Added
    Removed
    Replaced
    Cleared
End Enum

Public Class Demo

    Public Shared Sub Main() 

        Dim dinosaurs As New Dinosaurs

        AddHandler dinosaurs.Changed, AddressOf ChangedHandler

        dinosaurs.Add("Psitticosaurus")
        dinosaurs.Add("Caudipteryx")
        dinosaurs.Add("Compsognathus")
        dinosaurs.Add("Muttaburrasaurus")

        Display(dinosaurs)

        Console.WriteLine(vbLf & "IndexOf(""Muttaburrasaurus""): {0}", _
            dinosaurs.IndexOf("Muttaburrasaurus"))

        Console.WriteLine(vbLf & "Contains(""Caudipteryx""): {0}", _
            dinosaurs.Contains("Caudipteryx"))

        Console.WriteLine(vbLf & "Insert(2, ""Nanotyrannus"")")
        dinosaurs.Insert(2, "Nanotyrannus")

        Console.WriteLine(vbLf & "dinosaurs(2): {0}", dinosaurs(2))

        Console.WriteLine(vbLf & "dinosaurs(2) = ""Microraptor""")
        dinosaurs(2) = "Microraptor"

        Console.WriteLine(vbLf & "Remove(""Microraptor"")")
        dinosaurs.Remove("Microraptor")

        Console.WriteLine(vbLf & "RemoveAt(0)")
        dinosaurs.RemoveAt(0)

        Display(dinosaurs)

    End Sub

    Private Shared Sub Display(ByVal cs As Collection(Of String)) 
        Console.WriteLine()
        For Each item As String In cs
            Console.WriteLine(item)
        Next item
    End Sub

    Private Shared Sub ChangedHandler(ByVal source As Object, _
        ByVal e As DinosaursChangedEventArgs)

        If e.ChangeType = ChangeType.Replaced Then
            Console.WriteLine("{0} was replaced with {1}", _
                e.ChangedItem, e.ReplacedWith)

        ElseIf e.ChangeType = ChangeType.Cleared Then
            Console.WriteLine("The dinosaur list was cleared.")

        Else
            Console.WriteLine("{0} was {1}.", _
                e.ChangedItem, e.ChangeType)
        End If
    End Sub

End Class

' This code example produces the following output:
'
'Psitticosaurus was Added.
'Caudipteryx was Added.
'Compsognathus was Added.
'Muttaburrasaurus was Added.
'
'Psitticosaurus
'Caudipteryx
'Compsognathus
'Muttaburrasaurus
'
'IndexOf("Muttaburrasaurus"): 3
'
'Contains("Caudipteryx"): True
'
'Insert(2, "Nanotyrannus")
'Nanotyrannus was Added.
'
'dinosaurs(2): Nanotyrannus
'
'dinosaurs(2) = "Microraptor"
'Nanotyrannus was replaced with Microraptor
'
'Remove("Microraptor")
'Microraptor was Removed.
'
'RemoveAt(0)
'Psitticosaurus was Removed.
'
'Caudipteryx
'Compsognathus
'Muttaburrasaurus
Version Information
Universal Windows Platform
Available since 4.5
.NET Framework
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Windows Phone
Available since 8.1
Thread Safety

Public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

A Collection can support multiple readers concurrently, as long as the collection is not modified. Even so, enumerating through a collection is intrinsically not a thread-safe procedure. To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.

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